Environmental news from California and beyond

Colorado River parks threatened by dams, report finds

April 26, 2011 | 8:10
pm

A report released Tuesday reiterates one of Western environmentalists' biggest gripes -- the network of dams along the Colorado River have irrevocably transformed the habitats of some of the country's most treasured national parks.

The dams make the flow of water along the river erratic, changing river temperatures as well as its shape, damaging fragile ruins and pushing native species to the brink, according to the report from the National Parks Conservation Assn.

"Without proper management, the landscapes that make the national parks located on its banks and its tributaries so incredible will be severely diminished, irreparably damaging in about a century’s time iconic ecosystems that was slowly formed over a period of 6 million years,” said David Nimkin, the southwestern regional office director of NPCA.

For example, in Dinosaur National Monument, Grand Canyon National Park and Black Canyon of the Gunnison National Park, the Colorado and its tributary of the Gunnison used to flood each spring, washing away large plants from river banks. But the floods have been eased by dams upriver from the parks, according to the report, and riparian vegetation has overtaken some of the banks. In the Grand Canyon, campsites that were once available on the sandy banks of the Colorado decades ago are now overgrown, the report says.

On Lake Powell -- created by the Glen Canyon dam, ferociously and unsuccessfully fought in the 1950s by environmental groups -- receding water levels have made ancient petroglyphs and ruins suddenly accessible to recreational boaters, with little protection by park staff, the report says.

It contends that many of the issues could be managed without seriously affecting the hydroelectrical power that the network of dams on the river and its tributary provide to the rapidly-growing region.